Hi Starry, I looked online and found some info for you. Forum guidelines here don't allow us to post links to ebay or other dealers' items currently for sale, but if you go to sites such as Ebay, Musicians Friend, Reverb, or Guitar Center, (and do a search for Hofner Bass guitar strap) they have photos of the guitar strap you're wanting info about, that they're selling, and the listings give more info about it, and its history, etc. At least that can get you started! :)

This is another photo of a guitar strap Paul had in "Help!" He probably had several so not sure if it's the same one as in your photo, but very well could be.

[This is an ] accurate reproduction of the strap originally used by Paul McCartney on his Hofner Violin Bass with the Beatles. This is an important detail to making your Beatle bass rig correct.

The strap is made of dark, chocolate brown leather, and includes a "dog clip" on one end of the strap (as Paul's did). One may either clip this dog clip to the tailpiece of the guitar, or to a short leather straplet (included) that replaces your strap button near the bridge. The straplet has a metal "D" ring to accept the dog clip.

Use this with any German made Hofner Beatle bass or the Hofner Contemporary Series Beatle Bass. This strap does not work with the Hofner Icon or Ignition Series basses due to the way the neck attaches to the body.